It is highly rational and, therefore, very desirable to produce an artificial leather from a fibrous sheet which has been produced from extremely fine synthetic fibers provided by a direct spinning method. However, this process involves a number of difficulties and, therefore, has never been successful in the actual production of artificial leathers.
Various processes have been attempted for producing a fibrous sheet by direct-spinning extremely fine fibers and by forming a web from the extremely fine fibers. For example, a spun-bond method, a melt-blow method, and a flush-spinning method are three different typical methods for producing an extremely fine fiber sheet.
In Japanese Patent Application Laid-open No. 53-31866 (1978), the inventors of the present invention disclosed an artificial leather in which a substrate comprising a web made from extremely fine fibers provided by a melt-blow method, which web is a typical spun-laid web, and a woven or knitted fabric is impregnated with an elastic polymeric material.
The above-mentioned artificial leather was disadvantageous in the following points.
1. The spun-laid extremely fine fiber web layer is easily peeled from the fabric layer at a relatively small peeling force.
2. The piles consisting of the spun-laid extremely fine fibers and formed on the raised surface of the artificial leather are easily removed from the raised surface so as to result in the undesirable exposure of the elastic polymeric material impregnated in the artificial leather and, sometimes, of the substrate consisting of the woven or knitted fabric in which the elastic polymeric material is impregnated.
3. The impregnation property of the elastic polymeric material into the composite sheet is poor and, sometimes, the impregnation of the elastic polymeric material in the composite sheet is uneven.